I don't think it's going to die as quickly as you think - it's a pretty sticky product. The network effects that made it attractive might kill it pretty fast when they evaporate, but it's going to be a major player in adtech for at least a decade, which might just give it time to be "saved" by some of the plays they're now pivoting towards.

On the ethics thing: they introduced some mechanisms around this, but the appointment of Nick Clegg to drive this as head of "Global Affairs" was always an eyebrow-raiser for those even slightly politically aware in the UK, and predictably less effective than FB management needed him to be (note: I voted Lib Dem in 2010 because I believed in his leadership - it's what he did next that showed the warning signs).

I think another quarter of decline and we might see a major shake-up, and I wouldn't be amazed to see Whatsapp getting payment (including crypto) functionality as a bit of Hail Mary to build another social network moat.